January 31, 2006

Persistence or Permanence?

Sean argues for the network-value of a naming convention for
URLs, namely, the inclusion in URLs-of-permanent-intent of the string ‘purl’. When I first read his post, my egocentrism led me to think he was alluding to the PURL system, launched by OCLC a dozen years ago
in response to our frustrations with the ground-hog-day character of the URN
meetings in the IETF. We launched PURLs
with an expectation that they would be widely adopted and deployed by all
right-thinking Web managers (we had a LOT of silly ideas like that…). PURLs have never been as widely deployed as
were our hopes, but they are still alive and growing, and remain both useful
and an instructive data point in the evolution of the Internet naming architecture.

One reason I was so ready to conclude that Sean was talking
about PURLS is his argument:

I am
thinking of nothing more complicated than a social naming convention. What if
permanent URLs contained the fragment '/purl/' for example? Would that not do
the trick? As a consumer, I look at example.com/purl/info12.html and can
immediately infer that it is a good candidate for bookmarking.

From a URL consumer's perspective, this would be very handy I think. From a URL
producer's perspective, it would also be very handy. In effect, it would allow
URL producers to send out signals to the world. One signal would be: 'this URL
is a good bookmark candidate. We won't be changing it and even if we change our
systems internally, we will make every effort to ensure that this link will
continue to work.'. The second signal would be 'This URL is not a good bookmark
candidate. Bookmark it at your own risk.' Simply leaving '/purl/' out of a URL
would send the latter signal.

No
new technology added! An approach predicated
on the URL-equivalent of a smilie, a token that says that someone
is looking after this identifier. It is
an important component of the added-value that we envisioned for PURLs, as it
happens. People will see http://purl.og/.... and say... hey, a URL for the long haul. OK… we’re not exactly talking
a firestorm of adoption. But the point was true
then and true today.

Back to
permanence and persistence. As I harbored
the delusional notion that Sean was
singing about our PURLy fates, I thought… “oh… he got the P part wrong
(invoking the word permanent rather than persistent)” It would appear, in fact, that he had arrived independently at a
related acronym.

The distinction is small, but important. What can permanence mean in a technological
world where only one of twenty students in a masters level information science
class recognized the phrase NCSA Mosaic? (Well, it means that change is unrelenting and
they don’t listen to big band music much either). And follow this link (top of the Google search set), if you think I'm blowing smoke:

NCSA Mosaic Home PageCreation and history of the browser. All versions available for download.archive.ncsa.uiuc.edu/SDG/Software/Mosaic/

I feel unlucky.

Even in
the hallowed halls of LibraryLand, we are (justly)
reluctant to talk about preservation in terms longer than the odd millennium. Much of the discussion surrounding business models
for digital preservation has to do with service contracts and the cost of assuring the integrity of a given bitstream for a given interval. It is NOT permanence we’re talking
about. It is persistence. And the definition refers to a business
process more than it does to a point in the past or future.

If you
have an identifier used for tracking the progress of a laptop from its point of
manufacture in Shanghai to your doorstep, the business process that is
identified (a shipment of a consumer good) is concluded in a period measured in
hours or days (mine took 40 hours). Soon
after, the identifier is so much digital chaff, duty done. But certainly
persistent in the context of its intended use.

If we’re
talking about cultural heritage assets, we have expectations measured in centuries. In either case, the success of the identifier
is tied to the life cycle of the asset or process, not to a calendar. Thinking of our identifiers in these terms
helps avoid staring towards a vanishing point. Sometimes.

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Tracked on January 31, 2006 at 06:54 PM

Comments

Sean argues for the network-value of a naming convention for
URLs, namely, the inclusion in URLs-of-permanent-intent of the string ‘purl’. When I first read his post, my egocentrism led me to think he was alluding to the PURL system, launched by OCLC a dozen years ago
in response to our frustrations with the ground-hog-day character of the URN
meetings in the IETF. We launched PURLs
with an expectation that they would be widely adopted and deployed by all
right-thinking Web managers (we had a LOT of silly ideas like that…). PURLs have never been as widely deployed as
were our hopes, but they are still alive and growing, and remain both useful
and an instructive data point in the evolution of the Internet naming architecture.

One reason I was so ready to conclude that Sean was talking
about PURLS is his argument:

I am
thinking of nothing more complicated than a social naming convention. What if
permanent URLs contained the fragment '/purl/' for example? Would that not do
the trick? As a consumer, I look at example.com/purl/info12.html and can
immediately infer that it is a good candidate for bookmarking.

From a URL consumer's perspective, this would be very handy I think. From a URL
producer's perspective, it would also be very handy. In effect, it would allow
URL producers to send out signals to the world. One signal would be: 'this URL
is a good bookmark candidate. We won't be changing it and even if we change our
systems internally, we will make every effort to ensure that this link will
continue to work.'. The second signal would be 'This URL is not a good bookmark
candidate. Bookmark it at your own risk.' Simply leaving '/purl/' out of a URL
would send the latter signal.

No
new technology added! An approach predicated
on the URL-equivalent of a smilie, a token that says that someone
is looking after this identifier. It is
an important component of the added-value that we envisioned for PURLs, as it
happens. People will see http://purl.og/.... and say... hey, a URL for the long haul. OK… we’re not exactly talking
a firestorm of adoption. But the point was true
then and true today.

Back to
permanence and persistence. As I harbored
the delusional notion that Sean was
singing about our PURLy fates, I thought… “oh… he got the P part wrong
(invoking the word permanent rather than persistent)” It would appear, in fact, that he had arrived independently at a
related acronym.

The distinction is small, but important. What can permanence mean in a technological
world where only one of twenty students in a masters level information science
class recognized the phrase NCSA Mosaic? (Well, it means that change is unrelenting and
they don’t listen to big band music much either). And follow this link (top of the Google search set), if you think I'm blowing smoke:

NCSA Mosaic Home PageCreation and history of the browser. All versions available for download.archive.ncsa.uiuc.edu/SDG/Software/Mosaic/

I feel unlucky.

Even in
the hallowed halls of LibraryLand, we are (justly)
reluctant to talk about preservation in terms longer than the odd millennium. Much of the discussion surrounding business models
for digital preservation has to do with service contracts and the cost of assuring the integrity of a given bitstream for a given interval. It is NOT permanence we’re talking
about. It is persistence. And the definition refers to a business
process more than it does to a point in the past or future.

If you
have an identifier used for tracking the progress of a laptop from its point of
manufacture in Shanghai to your doorstep, the business process that is
identified (a shipment of a consumer good) is concluded in a period measured in
hours or days (mine took 40 hours). Soon
after, the identifier is so much digital chaff, duty done. But certainly
persistent in the context of its intended use.

If we’re
talking about cultural heritage assets, we have expectations measured in centuries. In either case, the success of the identifier
is tied to the life cycle of the asset or process, not to a calendar. Thinking of our identifiers in these terms
helps avoid staring towards a vanishing point. Sometimes.